Filters and filter material for use in filtering tobacco smoke



Uni t e Pate tQ FILTERS AND FILTER MATERIAL FOR USE IN FILTERING TOBACCOSMOKE Jan Ivo Marek, Margate, England, assignor of one-half to AndersJordahl, New York, N. Y.

No Drawing. Application May 23, 1955, Serial No. 510,538

Claims priority, application Great Britain October 8, 1954 Claims. (Cl.131--10) This invention relates to filter material for use in filteringtobacco smoke and to filters incorporating this material.

There has recently been considerable research in various countriesconcerning the effects of tobacco smoke on the human lungs and othervital organs and it has been demonstrated that tobacco smoke has atendency to produce lung cancer and may also have a bad effect on theheart and other organs.

The alleged carcinogenic substances in tobacco smoke include certainaromatic hydrocarbons comprising dibenzanthracene II and benzpyrene,nicotine and other compounds. It is desirable to remove thesecarcinogenic substances from the smoke as far as possible while allowingnon-toxic constituents of the smoke to pass to the smoker. Variousfilters having a purely mechanical action have been proposed but sincesome at least of the carcinogenic substances are gaseous in tobaccosmoke these filters do not provide effective protection for the smoker.The object of the invention is to provide filter material capable ofabsorbing substantial proportions of the carcinogenic substances.

The filter material in accordance with the invention comprisescellulosic material to effect mechanical filtering of the smoke incombination with carbon in porous or finely divided form and of at least96% purity, and preferably of at least 99% purity, the carbon beingobtained by a wet process from lignin produced in the manufacture ofpaper by the soda process and heated with concentrated sulphuric acid ata temperature of over 220 C. e. g. for five to six hours, the carbonbeing treated subsequently with steam.

The treatment to which the carbon is subjected in accordance with thepresent invention differs in only limited respects from that describedin applicants copending application, Serial No. 232,162, filed June 18,1951, now abandoned, and reference may be had to that specification fora more complete understanding thereof. Essentially, it is suggestedthere that the residual liquor obtained in the manufacture of paper pulpaccording to the well known caustic soda process, which liquor containslignin as its principal solid constituent, is concentrated byevaporation of water to a thick paste and the paste is treated with aweak acid, such as sulphuric or hydrochloric acid of 16-22 B., in largeenough quantities to precipitate the lignin. The lignin is separated bydecantation, filtered and dried at a temperature not exceeding 90 C.After drying, it is treated with turpentine or alcohol at a temperatureof about 60 C. in order to extract the resins and various otherimpurities therefrom. The purified lignin is treated with a mixture ofthree parts by volume of sulphuric acid and one part of hydrochloricacid at an elevated temperature below 100 C. and thereafter withconcentrated sulphuric acid, of at least 62 B. at a substantially highertemperature, which according to the present invention is 220 C. ratherthan 200 C. as specified in the prior application. The carbon formed by"the action of the acid on the lignin is treated with hydrochloric acidat normal temperature, washed with distilled water, and dried at normaltemperature.

It is desirable in some applications of the filter material that thecarbon should possess sufl'icient strength to retain a porous structure.

It is advisable to wash the carbon with an alkaline solution beforetreating it with steam.

The proportions of the various carcinogenic substances in tobacco smokevary with different kinds of tobacco and for 'each' tobacco the mostsuitable kind, and amount, of cellulosic material should be chosen. Ingeneral the cellulose should be chiefly alpha cellulose with a lessersamount of beta cellulose.

The filter material according to the invention can be incorporated infilters in various ways. The carbon, in finely divided form, may heintimately associated with cellulose wool or paper, or with tobaccoitself, or the cellulosic material may take the form of a pair of plugsof cellulose wool or paper one at either end of a tubular supportbetween which plugs the carbon is situated.

Filters in accordance with the invention can be provided on individualcigarettes or cigars as tips, or they may be provided in cigarorcigarette-holders or in tobacco pipes. In the latter case the filtersmay be in the form of throw-away filter elements: the cigarorcigarette-holders may also be of throw-away paper type. Filters providedin individual cigarettes or cigars should be of a length sufficient toabsorb all or most of the carcinogenic substances produced on burningthe cigarette or cigar.

I claim:

1. 'Filter material for use in filtering tobacco smoke comprisingcellulosic material to effect mechanical filtering of the smoke, andcarbon in combination therewith, in a form penetrable by smoke and of atleast 96% purity, the carbon being obtained by a wet process from ligninproduced in the manufacture of paper by the soda process and heated withconcentrated sulphuric acid at a temperatureof over 220 C. the carbonbeing treated subsequently with steam.

2. Filter material as claimed in claim 1, wherein the carbon is of atleast 99% purity.

3. Filter material as claimed in claim 1, wherein the carbon isintimately associated with cellulose wool.

4. Filter material as claimed in claim 1, wherein the carbon isintimately associated with paper.

5. Filter material as claimed in claim 1, wherein the cellulosicmaterial is tobacco and the carbon is intimately associated therewith.

6. Filter material as claimed in claim 1, wherein in production of saidcarbon, the lignin is heated for five to six hours.

7. A cigarette having a filter tip comprising cellulosic material toeffect mechanical filtering of the smoke, and carbon in finely dividedform, the carbon 'being intimately associated with the cellulosicmaterial and being obtained by a wet process from lignin produced in themanufacture of paper by the soda process and heated with concentratedsulphuric acid at a temperature of over 220 C. the carbon being treatedsubsequently with steam.

8. For a tobacco-smoking device including a tube for smoke from thetobacco and means for removably locating a filter in the path of smokepassing through said tube, a throw-away filter comprising cellulosicmaterial to effect mechanical filtering of the smoke, and carbon incombination therewith, in a form penetrable by smoke and of at least 96%purity, the carbon being obtained by a wet process from lignin producedin the manufacture of paper by the soda process and heated withconcenice References Cited in'the' file ,of-this patent UNITED STATES,PATENTS 729,680 -Swartz... June'2,'1903 4 Bradford Oct. 5, 1909Broadway .."July 19, 1932 Sadtler Dec. 25, 1934 Donnelly Apr. 10, 1945FOREIGN PATENTS Great'Britain Oct. 30, 1930 Great Britain July 27, 1933Great Britain Dec. 19, 1938

1. FILTER MATERIAL FOR USE IN FILTERING TOBACCO SMOKE COMPRISINGCELLULOSIC MATERIAL TO EFFECT MECHANICAL FILTERING OF THE SMOKE, ANDCARBON IN COMBINATION THEREWITH, IN A FORM PENETRABLE BY SMOKE AND OF ATLEAST 96% PURITY, THE CARBON BEING OBTAINED BY A WET PROCESS FROM LIGNINPRODUCED IN THE MANUFACTURE OF PAPER BY THE SODA PROCESS AND HEATED WITHCONCENTRATED SULPHURIC ACID AT A TEMPERATURE OF OVER 220*C. THE CARBONBEING TREATED SUBSEQUENTLY WITH STEAM.